Brush construction of optimum working bristle length



1961 L. E. .JQNES ,01,l3

BRUSH CQNSTRUCTION OF OPTIMUM WORKING BRISTLE LENGTH Filed April 3, 1958 2 Sheets-Sheet l 40x0 E: dBA/ES INVENTOR.

Nov 28, 11 L... E. JONES 3gmgl3g BRUSH CONSTRUCTION OF OPTIMUM WORKING BRISTLE LENGTH Filed April 3, 1958 2 Shams-Sheet 2 II n g KW Z6 f iLm o Q INVENTOR.

atent fiice 3,010,132 Patented Nov. 28, 1961 3 010 132 BRUSH CONSTRUCTI ON 9F UPTIMUM WURK- ING BRISTLE LENGTH Lloyd E, Jones, Arcadia, Calif, assignor to Industrial Brush Company, Arcadia, Califi, a corporation of California No. 726,156 (Cl. 15-183) Filed Apr. 3, 1958, Ser.

2 Claims.

by power-driven means which exemplifies the utility of I a brush means constructed according to the invention.

Conditions for sweeping a street vary considerably during different periods of the year and in different geographic areas. In Eastern States, cinders and salt are spread on snow in winter to give automobiles traction, and in the spring clean-up, street sweeper operators prefer a broom or brush with short, stifi? bristles to sweep the cinders and salt. In the West, rains wash dirt and sand from the mountains onto the streets, and to sweep dirt and sand a broom with short and stiff bristles is desirable. At other times of the year dust and refuse collected on the streets can be more effectively swept by a brush with a longer and less stiff bristle.

In view of the widely variant street sweeping conditions, prior proposed street sweeping brushes or brooms have included brush bristle or broom filaments of relatively thick or large diameter in order to give the bristle or filament proper stiifness when the broom is new. Such sweeper brooms, when new, included a bristle length which was much greater than the most efi icient, effective working bristle length as determined by street sweeping condition and the characteristics of the material used in the broom or brush filament. Such excess length in prior proposed broom constructions was required in order to give a suitable life to the street sweeping broom. For example, prior proposed broom filament length on a cylindrical street sweeping broom having an outer diameter of 36 inches included a filament length of 12 inches. Often the material used in such a filament length has a most optimum effective working length of 4 or 5 inches. The extra 7 or 8 inches of length'was provided to give substantial brush life and to avoid the costs of labor and machine down-time in frequent chang ing of street sweeping brooms.

When such prior proposed cylindrical brush constructions became worn, the outer diameter of the brush was reduced. The axis of rotation of the brush was then downwardly adjusted in the street sweeping machine for proper contact of the bristle ends with the street surface. Street sweeping machines are provided with battles adjacent the internal enclosed portions of the brush in order to confine the lighter particles of refuse and dust swept into the machine by the brush means. When the brush is new, the bristles maintain relatively close tolerance with such baffies. As the brush becomes worn however, space between the circumference of the brush and the battles increases with the result that when the brush is about two thirds 'worn, a turbulent air condition is created wherein light particles of refuse and dust are carried over the brush and discharged. Such carry over of the dust and refuse becomes considerable and the machine redistributes part of the dust and light refuse about the street.

As the brush wears, the working length of the bristle tends to become stiffer and as a result the partially worn brush presents to the street surface an ever stiffening bristle which becomes too stiff to pick up certain material on the street or to clean out the numerous small cavities and depressions in the street surface which are best swept by a less stiff bristle. The wearing of the brush not only produces a stiffer brush but the peripheral speed of the outer circumference of the worn brush continually varies with respect to the linear speed of the machine. As a result, a prior proposed brush which is designed for a particular life period is utilized in a plurality of continually changing sweeping conditions; for which at virtually no time is a prior proposed brush opening at its optimum effectiveness. Another 'disad:

vantage of the prior proposed brush constructions was that the broom filament was flexed or bent about only one point, namely, the point where the filament entered the metal strip holder or clamp and many bristles would break off as a result of fatigue stresses before the end of the normal life period of the bristle.

The present brush construction contemplates a novel brush means which will obviate all of the disadvantages mentioned above of prior proposed brush constructions as related to sweeping operations and wherein regardless of Wear on the brush bristle or filament, the brush means" may be operated at optimum 'eificiency and effectiveness during the entire life of the brush means.

A main object of this invention therefore is to provide and disclose a novel brush construction wherein the brush means is capable of operating as a new brush even though it is worn and has almost reached the end of its life.

An object of this invention is to design and disclose a brush construction having a uniform circumference regard-less of wear upon the brush.

Another object of this invention is to disclose abru'shconstruction wherein an optimum effective: working bristle length is provided during virtually the entire life of the brush. p

A further object of this invention is to design and disclose a brush construction wherein brush filament fatigue is distributed throughout a major portion of thelength of the filament during the life of the brush.

A still further object of this invention is to disclose and provide a brush construction wherein the filament, effective workinglength maybe readily adjusted to prolength for the street sweeping j vide an optimum working condition encountered.

Still another object of this invention is to disclose and provide a brush construction wherein a bristle filament length of the smaller diameter filament so that suchfilament may clean refuse requiring stiif bristles and still provide fineness for clean sweeping.

The invention contemplates a brush construction wherein brush bristle means are provided with bristle or filaments fixed at one end and having free ends and wherein fulcrum means are provided for said bristle betweentheir fixed and free ends, said fulcrum means being positioned at a distance from the free ends of the bristles for providing an optimum working length of the bristle. v

A morespecific object of this invention is to disclose and provide a brush construction as mentioned above wherein means are provided for relative displacement of the bristle means and the fulcrum means between the members being spaced apart to form longitudinally extending slots. Radially inwardly of said slots are provided a plurality of brush strips in alignment with associated slots and having bristles extending through said slots and projecting outwardly therefrom a preselected distance which provides an optimum working bristle length for the street sweeping condition for which the brush means is intended to be employed. Means are provided for supporting said brush strips on the end plates for adjustmentr-adially outwardly to maintain the optimum working length of the bristles to compensate for wear at the free ends thereof.

Numerous objects and advantages of the present invention will be readily apparent to those skilled in the art from the following description of the drawings in which an exemplary embodiment of the invention is shown.

In the drawings:

FIG. 1 is a longitudinal sectional view taken through a cylindrical brush construction embodying this invention, the section being taken in a plane passing through the axis of the cylindrical brush construction.

FIG. 2 is a transverse fragmentary sectional view of the brush means shown in FIG. 1, the section being taken in a transverse plane indicated by line IIII of FIG. 1.

FIG. 3 is a fragmentary sectional view taken in the same plane as FIG. 2, and illustrating the position of brush filaments after considerable wear on the brush bristles.

'FIG. 4 is an enlarged fragmentary sectional view taken in the same vertical plane as FIG. 1 and showing an end of the brush means.

FIG. 5 is an enlarged transverse fragmentary sectional view similar to FIG. 2.

FIG. 6 is a schematic fragmentary view of a street sweeping machine equipped with a brush construction of the present invention.

The schematic drawing of a street sweeping machine generally indicated at 10 in FIG. 6 illustrates a brush means 11 constructed according to this invention and mounted thereon for rotation by power driven means in well known manner. The brush means 11 may be supported in a compartment 12 provided with a front baflle wall 13 and a back bafile wall 14 whereby dust and dirt carried over by brush means 11 may be contained within chamber 12 and may be prevented from being discharged forwardly of Wall 13 by rotation of the brush means 11. In normal operation, the brush means 11 sweeps material and refuse from a street surface 15 onto a suitable power driven upwardly inclined conveyor belt means 16 which discharges said material into a refuse dump chamber 17. The other details of the street sweeping machine are not shown because they are not part of this invention and are well known in the art. It will be readily apparent from FIG. 6 that the bottom edges 18 and "19 respectively of bafile walls 13 and 14 are provided relatively close tolerance to the circumference of the brush means 11 and it will be understood that the brush means 11 (as later described) maintains the diameter indicated at D (FIG. 1) throughout its entire life.

The brush means 11 may be suitably mounted on a hollow axle 23-connected to driving means and sup-' ported from hearing means (not shown) in well known manner. Secured to each end of axle 23 may be a circular end plate 25 of a selected diameter less than the maximum diameter of the brush means 11. In this example, each end plate 25 may be seated in a recess 26 provided at the end of axle 23 and secured to the axle as by welding. A plurality of circumferentially spaced longitudinally extending bristle engagement tubes or members 28 extend between and interconnect the end plates 25. In this example, the engagement members 28 are tubular for lightness and strength but it is understood that they may be solid bars or any other suitable metal configuration, section, or material. The engagement 4 members 28 are spaced apart a selected distance so as to provide a plurality of longitudinally extending slots or openings 29 through which the bristles of the brush means may extend. The engagement members 28 are 5 provided with curved surfaces 30 against which the bristle members may contact and bend as about a fulcrum. It will be understood that the slots 29 may be of slightly less width than the thickness of a layer of brush bristles passing therethrough so as to lightly hold or retain the layer of bristles at that area. It will also be understood that the axes of the engagement members '28 may be spaced further apart and the members 28 may have greater width so as to vary the density of the bristle structure at the exterior of the brush means.

The brush means 11 may also include a plurality of longitudinally extending brush strip means generally indicated at 32, each brush strip means 32 including a prefabricated assembly of brush bristles or broom filaments 33 carried by and secured in a generally U-shaped channel base member 34 of metal, the filaments being clamped in said base member 34 for providing thereat a fixed end for the filaments 33. The bristle filaments 33 may be made of selected natural or synthetic fibre having predetermined size, length, diameter, stiffness, and bending or flexing characteristics. Each base member 34 of the brush strip means 32 may be secured and held in an elongated brush holder 36 of U-shape and having top longitudinally extending edge margins 37 on side walls thereof crimped or bent inwardly to retain the base members 34 therein. At each end the holder 36 may be provided with a square nut 39 nonrotatably secured therein in any suitable manner, said nut 39 having a threaded bore to receive a stud bolt 40.

Means for securing the brush strip means 32 in selected position between end plates 25 may comprise a plurality of radially outwardly spaced ports or openings 42 in radial alignment with spaces 29 between the engagement members 28. Each opening 42 may receive the stud bolt 40 which may be inserted therethrough tor threaded engagement with nut 39 held in the holder 36. Thus holders 36 may be adjusted radially outwardly by moving the holders into alignment with respective aligned openings 42. It will be understood that various other means may be provided for securing the holders 36 to the end plates.

In the brush construction described above, it will be readily apparent that brush means 11 is provided a diameter D which may be maintained constant throughout the entire life of the brush by intermittent radially outward adjustment of holders 36 by means of radially aligned openings 42 in end plates 25. In such radial outward adjustment, it will be readily apparent that the free ends of the brush filaments 33 are spaced radially outwardly a selected distance from the bnishengagement members 28, such distance being the optimum effective working length of the particular brush filament used in the brush strip means and for the particular sweeping condition to v be encountered. In FIG. 1 the optimum eitective working length of a bristle is indicated at L. As the free ends wear in use, the brush strip means 32 are moved progressively outwardly until they reach the position shown in FIG. 3 where brush bristles 33 are at optimum length L but thereafter wearing of the brush bristles Will poduce a bristle of a length less than optimum. It will be readily understood that in accordance with the present practice of using street sweeping brushes, the bristle length as shown in FIG. 3 may still be used to a selected length which is less than optimum.

to flexing and bending about base member 34. Obviously such a length of bristle is of much greater length than required for a particular job. In the present brush constructipn utilizing only the length of bristle determined It is important to note that base member 34 holdsone end of bristles 33 fixed in relation to the brush construc- A to be the optimum length L as indicated, the brush bristles 33 are supported intermediate their ends at curved surfaces 30 on the brush engagement members 28. The support of the bristles at an intermediate portion of their length is along a curved surface so that no sharp edges are in contact with the brush bristles and the curved surfaces 30 provide a fulcrum surface or a fulcrum means about which the bristles may bend during a sweeping operation. Substantially all of the bending of the bristle occurs at curved surfaces 30 so that fatigue of bristle material does not occur at the fixed end at the clamped edges of base member 34. As the bristles become worn and the holders 36 are advanced radially outwardly the intermediate portions of the bristle filaments 33 which engage the fulcrum surface 30 is changed so that at no time does a particular fixed portion or intermediate length of the brush element become subject to bending throughout the life of the bristle. In this present invention, bending occurs progressively along the length of the bristle toward the fixed end so that fatigue of bristle material at the principal bending area is not sufficient to cause fatigue breaking of the bristles.

Since a virtually constant outward diameter of the brush means 11 is provided by the above described brush construction, it will be readily apparent to those skilled in the art that when such a brush means is employed in a street sweeping machine such as 10, the selected tolerance or clearance between edges 18 and 19 are maintained throughout the entire life of the brush means and turbulence and redistribution of the dust and dirt and leaves forwardly of the machine during operation is prevented. Moreover, the optimum speed of rotation of the brush means may be maintained since the peripheral speed of the brush will remain constant with respect to the linear speed of the machine, thus change in speed of rotation of the brush to maintain a predetermined relationship between linear speed of the machine and pe ripheral speed of the outer circumference of a brush means is not required.

It will be readily apparent to those skilled in the art that while the exemplary brush construction described above illustrates movement of the brush strip means 32. relative to the brush engagement members 28 in a radially outward direction, so as to maintain a most effective working length of the brush bristle outwardly of the engagement members, it will be understood that the engagement members 28 may be so mounted on the end plates 25 so as to provide selected radial adjustment of members 28 in order to maintain a brush means of a constant selected diameter while the optimum length of the bristle is made shorter or longer. Any such relative adjustment of the bristle means and the brush engagement members is contemplated by this invention so as to provide a brush means as described above.

It will be understood by those skilled in the art that the above described brush construction in actual effect provides a brush means which is equivalent to a new brush throughout virtually the entire life of the brush means because the optimum working length of bristle is maintained.

Various other modifications and changes maybe made in the brush construction described above and all such changes coming within the scope of the appended claims are embraced thereby.

I claim:

1. In a cylindrical brush construction for a machine for sweeping a street surface or the like, the combination of: an elongated brush core means having a length greater than the diameter of the brush construction and including a shaft defining an axis of rotation, bristle engagement means having opposed spaced surfaces providing longitudinally extending parallel continuous openings in said core means in circumaxial relation, and end plates on said core means; a plurality of brush strips extending in circumaxial relation between said end plates and between said shaft and said engagement means, each brush strip including a continuous layer of bristles projecting through a respective opening, each layer of bristles being laterally held by said opposed surfaces and projecting beyond said openings at selected distance; brush strip holder means extending between said end plates and adjustably connected therewith for supporting said plurality of brush strips from said core means, said brush strip holder means supporting said brush strips throughout their lengths, and having means in continuous engagement with said brush strips for uniformly retaining the brush strips throughout their length against radial outward displacement during rotation of the brush construction; and means on the end plates and means on the brush strip holder means for securing said holder means to the end plates and for radial adjustment of the holder means to compensate for wear of the projecting bristles.

2. A brush construction as stated in claim 1 wherein said brush strip holder means includes a pair of parallel walls receiving therebetween an associated brush strip, and wherein said means in continuous engagement with the brush strips includes converging edge portions of said pair of walls for grasping and retaining said brush strip continuously along the entire length of the brush strip.

References Cited in the file of this patent UNITED STATES PATENTS 1,168,849 Butler Jan. 18, 1916 1,766,388 Kovacs June 24, 1930 FOREIGN PATENTS 13,578 Great Britain Aug. 3, 1901 284,041 Switzerland Nov. 1, 1952 685,956 Great Britain Jan. 14, 1953 

